Overview

If you are feeling like you are not up to it, you are not alone, and science can explain what is happening to your libido.

Hormonal imbalances, especially involving oestrogen, testosterone, and cortisol, can affect sexual desire in both people assigned male and female at birth. Low testosterone in people assigned male at birth (AMAB) and low oestrogen in people assigned female at birth (AFAB) play key roles, but increased stress hormones (such as cortisol) and dysfunctions of the thyroid gland also play major roles. These imbalances can change the normal signalling that stimulates libido, affect mood and energy levels, and even lead to physical symptoms like vaginal dryness or erectile issues.¹ 

So you are not imagining it. 

Key hormones involved include:

• Testosterone – low levels linked to decreased desire in both sexes
• Oestrogen –  responsible for female libido and vaginal health
• Cortisol – chronic stress and high cortisol suppress sexual function
• Thyroid hormones – both hyper- and hypothyroidism can reduce libido

Hormonal imbalances are one of the major causes of decreased libido, so stick around as we walk you through why that is and what research so far has to say about it.

What is libido?

Sexual desire, also known as libido, is the body’s natural drive in sexual activity or intimacy. It is influenced by many factors, including:¹ 

• Emotional well-being 
• Relationships 
• Physical health
• Especially hormones

Hormones are chemical messengers that control many functions in the body, including sexual health. When these hormones are balanced, they help support a healthy libido. But when hormone levels become too high or too low, known as a hormonal imbalance, it can lead to reduced sexual desire.¹

Hormones involved in libido

Next, we will explore the different hormones that are involved in sexual desire. 

Testosterone

Testosterone is present in both people AMAB and AFAB; it is often called the “sex hormone” because of how much it affects libido. Even though people AMAB have higher levels than people AFAB, and in our minds, it is more often linked to people AMAB, it is essential for both because:²

• It increases libido, vitality, and confidence
• Low testosterone (also called testosterone deficiency) can lead to reduced interest in sex, low energy, and even mood changes

As people AMAB get older, their testosterone levels and sexual function naturally decrease. Other health problems, such as diabetes or obesity, can make this worse. Low testosterone can reduce sexual desire, but it’s not always the main cause of erectile dysfunction (ED) in older people AMAB.^2,3

Testosterone replacement therapy (TRT) can help some men, especially with boosting desire, but the results are different for everyone, and not always highly effective. In many cases, healthy lifestyle changes (such as exercise, diet, and quitting smoking) can help just as much as TRT.³

Oestrogen

Oestrogen plays a big role in female sexual health. It helps maintain the health of vaginal tissues, natural lubrication, and overall sexual sensitivity.⁴

Low estrogen, especially during menopause, can cause:⁴

• vaginal dryness and discomfort
• making sex less pleasurable 
• decreased desire

Oestrogen medicine, such as in hormonal replacement therapy (HRT), can help with these problems, but it’s not for everyone, because it may carry some risks, so it’s important to talk to a doctor first.⁴

Progesterone

Progesterone helps balance the menstrual cycle and can influence mood. When levels are too low or too high, it may lead to irritability, fatigue, and a low sex drive. Progesterone imbalances are common during pregnancy, after childbirth, and during perimenopause (the transitional period before menopause).⁵

Oxytocin and Dopamine

These are sometimes called “feel-good” hormones because:⁶

• Oxytocin is released during close contact, hugging, or intimacy, and helps create an emotional connection
  Dopamine plays a role in the brain’s reward system and is involved in feelings of pleasure and motivation, including sexual desire

Therefore, when these hormones are low, bonding and arousal may become weaker.⁶

Thyroid hormones

The thyroid gland regulates metabolism and energy and secretes hormones.⁷

• If thyroid hormones are underactive (a condition called hypothyroidism), people may feel tired, lethargic (sluggish), and uninterested in sex
  Thyroid disorders are known to affect mood, energy, and libido in people AMAB and AFAB

Causes of hormonal imbalances

Ageing

As people age, hormone levels naturally decline. In people AFAB, menopause leads to a drop in estrogen and testosterone. In people AMAB, andropause causes a gradual decrease in testosterone. This often leads to lower sexual desire and changes in mood or energy.^3,5

Chronic stress and cortisol

Long-term stress increases cortisol, a hormone that can interfere with the balance of other important hormones such as estrogen, testosterone, and thyroid hormones. This can reduce libido and lead to fatigue or mood swings.¹ 

Polycystic Ovary Syndrome (PCOS)

PCOS is a common condition in women where hormone levels are unbalanced. Women with PCOS often have higher levels of androgens (male hormones), which can disrupt ovulation, cause irregular periods, and affect sexual function.⁸

Thyroid disorders (hypothyroidism/hyperthyroidism)

The thyroid gland controls your body’s metabolism. When it’s underactive (hypothyroidism) or overactive (hyperthyroidism), it can cause tiredness, mood issues, and changes in sexual desire.⁷

Pituitary gland problems

The pituitary gland is like the control centre for many hormones in the body. If it’s not working properly, it can lead to hormone imbalances that affect sexual function, including low testosterone or oestrogen.⁹

Certain medications

Some medications, like antidepressants, birth control pills, or treatments for cancer (chemotherapy), can interfere with hormone levels and lower sexual desire.

Lifestyle factors

Poor sleep, unhealthy diet, lack of exercise, and high alcohol use can all affect hormone balance. Over time, these habits can reduce libido and general well-being.

Summary

Sexual desire is a natural and important part of overall health and well-being. When it starts to fade, many people feel confused or frustrated, but the truth is, you're not alone, and there are clear medical reasons behind it.

Hormones such as testosterone, estrogen, progesterone, cortisol, and thyroid hormones play key roles in regulating libido. When these hormones fall out of balance, whether due to age, stress, illness, or lifestyle, they can cause changes in sexual desire, energy, and mood.

Low libido is not just “in your head”; it's often a real, physical issue caused by hormonal changes. The good news is that identifying the cause is the first step toward finding a solution. In many cases, lifestyle improvements, stress management, or medical treatment can help restore balance and improve sexual well-being.

So if you’ve been feeling “off”, tired, or just not like yourself when it comes to intimacy, know that there is support, there are options, and it all starts with understanding what’s happening in your body.